Sudden Food Intolerances in Adults (and Possible Causes)

by JJ Virgin on January 10, 2023

Many years ago, I was teaching doctors how to use different types of functional labs in their practices, including food-sensitivity testing. This kind of testing is different from sudden food allergies, where someone opens a bag of peanuts, goes into anaphylactic shock, and could die.  

Instead, food intolerance is an umbrella term that includes the foods you’re sensitive to. The reaction is more subtle; you may get tired or feel cramping in your legs a few hours after you eat an offending food, for example. These are delayed symptoms to a food that you’ve developed over time. 

New food intolerances don’t occur overnight, but they may feel like they come out of nowhere when you suddenly develop reactions to a food that you’ve been eating for a while.  

Why do they happen? Genetic, immunological, or hormonal reasons often contribute to sudden food intolerances in adults.  

One sign when you develop a new food intolerance is that you start to crave the very foods that are hurting you. Suddenly, you have overwhelming cravings—and not for broccoli and salmon. Nope. It’s cravings for things like cheese and bread, which are very easy to overeat. 

4 Causes of Sudden Food Intolerance in Adults 

I’ve found that sudden food intolerance often occurs because of these four culprits. Read on to learn about them, along with five ways to heal your gut so you may be able to enjoy those foods once again. 

1. Leaky Gut  

From all my years of working with doctors and lab tests, I learned that almost anyone with food intolerance has some degree of leaky gut. 

Leaky gut is just what it sounds like. Ideally, your gut should let small, but not large, particles pass through. When your gut gets more permeable, however, things that aren’t supposed to get through do. 

The results are disastrous. A leaky gut lets bacteria and undigested food particles slip into your bloodstream. Your body responds to these invaders with an immune reaction that results in a wide range of gastrointestinal problems and inflammation.  

Numerous factors can contribute to leaky gut, including fructose and gluten, certain artificial sweeteners, genetically modified (GMO) foods, toxins, chronic stress, and even certain medications. Over time, these culprits take aim at your gut, creating havoc that eventually extends beyond digestion. 

Learn more about leaky gut here 

2. Dysbiosis 

Food intolerance can also occur when you have imbalances among the trillions of organisms that inhabit your gut. A high-functioning metabolism and your health depend on harmony between the good and bad bacteria in your gut. It is normal to have both kinds, yet when the balance is tipped in favor of the bad guys, food intolerance can result.  

Like leaky gut, dysbiosis can occur for many reasons. When you’re eating a low-fiber diet, you’re not feeding the healthy bacteria that support a healthy gut. Plus, when you constantly bombard your gut with sugary foods (as well as gluten, soy, and other problem foods that can create food intolerance), you’ve got a surefire formula to knock those bacteria out of balance. 

Read more about dysbiosis in this blog. 

3. Your Diet 

How does your gut bacteria get out of balance and result in problems like leaky gut and dysbiosis? First and foremost, by what you eat. 

It’s not just the sugary foods that create problems, either. Things like corn, gluten, and soy sneak in unsuspecting places like mustard, the grass-fed steak you order at your favorite restaurant, and many processed foods and beverages.  

You probably never suspected these “health” foods as the stealth attackers for your creeping weight gain, fatigue, brain fog, and other chronic symptoms. If you ate those foods rarely, antibodies would take care of those little food particles, like Ms. Pac-Man destroying them.  

Unfortunately, most of us eat the same stuff—gluten, dairy, soy, corn, peanuts, gluten, dairy, and eggs—regularly. When you’re constantly bombarding your gut with these problem foods, your body can’t get rid of those immune complexes.  

This activates immunoglobulin G (IgG) antibodies in what’s called a delayed immune response, and it keeps your immune system in constant gear. These IgG responses are chronic, low-grade, and develop over time, often without you realizing they’re happening. 

You may think these low-grade symptoms are normal. You may also be thinking, “Everybody gets tired in the afternoon. I just need another coffee,” or “It’s normal to feel a little gas and bloated or joint pain as I get older.” 

Couple that with bad digestive habits like not really chewing and drinking a ton of fluid during meals (which can lower stomach acid that breaks down protein), and you can understand how food intolerance develops.  

4. Stress 

I mentioned earlier how leaky gut can create food intolerance. While your diet is a big culprit, other factors create damage too, including medications. But the biggest driver that makes your gut leaky? Chronic stress. 

“Your gut is unhappy because of stress,” says Vincent Pedre, MD, in Happy Gut. “Research shows the stress response can alter the natural balance of healthy bacteria in your gut, causing the gut ecology to shift in favor of a more hostile group of bacteria.” 

Other studies show that stress and mood disorders such as depression compound each other and contribute to leaky gut and dysbiosis, creating an inflammatory response that starts in your gut, but like wildfire, spreads throughout your body.1 

How to Heal From Food Intolerance 

When I was running these tests with doctors and we were waiting for the labs to come back, I started pulling out the foods that were most common. People would come back for the test results already feeling better when they removed these foods. 

Over time, I found seven common foods were causing most of the problems. When I had people pull these foods for three to four weeks, they told me the first couple of days they were craving some of those foods like mad.  

By the end of the week, however, their joint pain was gone, their skin cleared up, headaches disappeared, and they didn’t have post-meal gas and bloating. I could safely assume that one of the foods was causing a problem. 

How long does it take to address food intolerance, stop new food intolerances, and heal your gut? That depends on how bad your gut was going in.  

I’ve found these strategies can help with all those issues. 

Get More Fiber  

Fiber can restore balance among the trillions of gut bacteria, support a strong overall gut, balance blood sugar, and much more.   

I want you to get 50 grams of fiber daily. Most people don’t get anywhere near that amount. If you’re currently low, add five grams of fiber every few days until you’ve hit your quota… and remember to drink plenty of water as you’re increasing fiber. Learn 15 of my favorite high-fiber foods here

Extra Fiber combines fiber derived from fruits, vegetables, roots, seeds, and tree extracts…including a prebiotic that supports the growth of friendly bacteria.* Altogether, it contains 12 types of fiber to create the ULTIMATE fiber product. You can only get it here. 

Incorporate Fermented Foods 

Fermented foods like sauerkraut and kimchi provide the probiotics your gut needs to support microbiome balance. Most of us don’t eat these regularly, which may explain why gut issues are so common. Learn more about fermented foods in this blog.

Take Gut-Healing Supplements 

While you’re eliminating the seven foods I mentioned earlier, you’ll also want to provide your gut with the nutrient support it needs to heal. My favorite gut-healing supplements include: 

  • Glutamine: The essential amino acid L-glutamine strengthens the intestinal wall after damage done by foods that cause food sensitivities, including gluten, soy, and dairy.
  • Omega Plus for anti-inflammatory support via the omega-3 fatty acids EPA and DHA, which your gut needs to heal.*
  • Designs for Health ProbioMed 50: This option provides 50 billion CFU per serving, with 10 of the most highly researched probiotic strains that support gut health.*  

Keep a Food Journal  

Being your own food detective involves making the connection between what you eat and how you feel. A food journal is the best way to do that. I used to tell clients, “I don’t really care what the test says. If the test says, ‘No, you’re fine with eating corn,’ but you eat corn and feel crappy, don’t eat corn!”  

Manage Stress  

Constantly feeling stressed out isn’t doing your gut—or much else, for that matter—any favors. Find stress management strategies that work for you. That might include yoga, meditation, deep breathing, walking your dog, or laughing with your bestie. Hear the most effective strategies I use to manage stress in this episode of Ask the Health Expert. 

Final Thoughts  

While new food intolerances may seem to come on suddenly, their development is a gradual process. As a result, it can be hard to connect the dots between what you eat, how you feel, and what you weigh.  

When you pull the seven foods I identified in The Virgin Diet out of your diet for just three weeks, amazing things happen. The weight falls off, your energy soars, your skin looks younger, your pain is gone, and your cravings are in the rearview mirror.  

Imagine not being a prisoner to that afternoon cookie or evening sweet. Imagine looking and feeling great in a few weeks by eliminating just seven foods from your diet.  

The Virgin Diet is the first step toward turning your weight and health goals into positive, everyday actions. It provides all the tools and resources you need to help you calm inflammation from hidden food sensitivities, reclaim your health, and feel energized and better than ever. * 

The views in this blog by JJ Virgin should never be used as a substitute for professional medical advice. Please work with a healthcare practitioner concerning any medical problem or concern. The information here is not intended to diagnose, treat, or prevent any disease or condition. Statements contained here have not been evaluated by the Food and Drug Administration. 

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. 


  1. Madison A, Kiecolt-Glaser JK. Stress, depression, diet, and the gut microbiota: human-bacteria interactions at the core of psychoneuroimmunology and nutrition. Curr Opin Behav Sci. 2019 Aug;28:105-110. doi: 10.1016/j.cobeha.2019.01.011. Epub 2019 Mar 25. PMID: 32395568; PMCID: PMC7213601.